Coordinate input device for calculating a coordinate of an input position of an applied vibration

Abstract

A shift of an input coordinate by a change in temperature in a coordinate input device is prevented. An arithmetic operation and control circuit 1 applies a drive signal to a vibration pen 3 and starts a timer. The drive signal applied to the vibration pen 3 is delayed by a delay circuit 12, which drives a vibrator drive circuit 2 to generate vibration. A delay time of the delay circuit 12 is shortened as a temperature rises and a sum time of the delay generated by the delay circuit 12 and a delay generated in the vibration pen 3 as the temperature changes is constant regardless of the temperature. As a result, a vibration propagation time measured by the timer represents a net propagation time plus a constant delay time regardless of the temperature. Thus, the stable coordinate input is assured regardless of the temperature.

What is claimed is: 
     
       1. A coordinate input device for detecting a vibration applied to a vibration transmitting member and calculating an input position of the vibration based on the detected vibration to produce a coordinate position as an input coordinate, comprising: detection means for detecting the vibration transmitting through said vibration transmitting member;   measurement means for measuring a time from the generation of the vibration to the detection by said detection means;   control means for controlling a timing to drive said measurement means;   delay means for delaying the drive timing of said measurement means by said control means in accordance with a temperature;   vibration input means for generating the vibration at the timing delayed by said delay means and inputting the vibration to said vibration transmitting member; and   derive means for deriving the coordinate of the input position of the vibration by said vibration input means based on the time measured by said measurement means.   
     
     
       2. A device according to claim 1, wherein said delay means includes a temperature sensitive resistor having a resistance varied in accordance with the temperature and a capacitor, and the delay time is determined by the resistance of said temperature sensitive resistor and the capacitance of said capacitor. 
     
     
       3. A coordinate input device for detecting a vibration applied to a vibration transmitting member and calculating an input position of the vibration based on the detected vibration to produce a coordinate position as an input coordinate, comprising: vibration input means for generating the vibration and applying the vibration to said vibration transmitting member;   control means for controlling a timing to drive said vibration input means;   detection means for detecting the vibration transmitting through said vibration transmitting member;   delay means for delaying the drive timing of said vibration input means by said control means in accordance with temperature;   measurement means for measuring a time before the vibration is detected by said detection means in accordance with the timing delayed by said delay means; and   derive means for deriving the coordinate of the input position of the vibration by said vibration input means based on the time measured by said measurement means.   
     
     
       4. A device according to claim 3, wherein said delay means includes a temperature sensitive resistor having a resistance varied in accordance with the temperature and a capacitor, and the delay time is determined by the resistance of said temperature sensitive resistor and the capacitance of said capacitor.